The present invention relates to an ultrasonic probe composed of a piezoelectric vibrator comprising an array of piezoelectric vibrator elements and an electrode plate with as many electrode patterns as the number of the piezoelectric vibrator elements, the piezoelectric vibrator elements and the electrode patterns being electrically connected to each other.
Ultrasonic probes having planar piezoelectric vibrators are heretofore known in the art. Other known ultrasonic probes have concave or convex piezoelectric vibrators for converging or diverging transmitted or received ultrasonic beams. Two electrode lead structures are known as described below.
One electrode lead structure is known as a wire bonding system in which, as shown in FIG. 10 of the accompanying drawings, wires 2 extend respectively from a lateral side 1a of one edge of a piezoelectric vibrator 1 and are connected to electrode patterns 3a, respectively, of an electrode plate 3. Alternatively, as shown in FIG. 11, wires 2 extending respectively from an upper side of one edge of a piezoelectric vibrator 1 are connected to electrode patterns, respectively, of an electrode plate 3.
The other electrode lead arrangement is an FPC (flexible printed circuit) system proposed by the inventor in Japanese Laid-Open Patent Publication No. 60-259247. As shown in FIG. 12, a first semicircular backing member 4B having a prescribed curvature has a surface on which a second backing member 4A is fixedly mounted. A piezo-electric vibrator array 1 is secured to the surface of the second backing member 4A. A matching layer 14 is fixed to the surface of the piezoelectric vibrator array 1, thus providing an ultrasonic probe body. An FPC plate 5 is attached to a side of the ultrasonic probe body. The FPC plate 5 comprises a plurality of thin laminated pieces 5a through 5f and having distal ends contacting the piezoelectric vibrator 1, the distal ends being divided into different groups 5a' through 5f'. The opposite ends of the thin laminated pieces 5a through 5f are also grouped into connectors 6a through 6f. Electrode lines L are formed on the thin laminated pieces 5a through 5f.
The arrangement shown in FIG. 10 is disadvantageous in that the configuration of the lateral side 1a of the piezoelectric vibrator 1 is often irregular, and that the thickness H of the piezoelectric vibrator 1 is small and so is the dimension of the lateral side 1a, with the result that no sufficient space is available for bonding the wires. According to the scheme shown in FIG. 11, since the wires 2 coupled to the upper side 1b of the piezoelectric vibrator 1 are curved upwardly, they would obstruct an acoustic matching layer on the piezoelectric vibrator 1.
With the FPC system, difficulty is experienced in making piezoelectric vibrator elements at sufficiently small pitches in a pattern of a small radius of curvature.